EduNinjaA magnet near a coil of wire is attracted to the coil only when there is a current in the coil.
Which statement explains this force of attraction?
The coil of wire has its own gravitational field.
The coil of wire is made from soft iron.
The current in the coil of wire creates a magnetic field.
The current in the coil of wire induces a charge on the magnet.
A magnet near a coil of wire is attracted to the coil only when there is a current in the coil. Which statement explains this force of attraction?
The coil of wire has its own gravitational field.
The coil of wire is made from soft iron.
The current in the coil of wire creates a magnetic field.
The current in the coil of wire induces a charge on the magnet.
A magnet near a coil of wire is attracted to the coil only when there is a current in the coil.
Which statement explains this force of attraction?
The coil of wire has its own gravitational field.
The coil of wire is made from soft iron.
The current in the coil of wire creates a magnetic field.
The current in the coil of wire induces a charge on the magnet.
The diagrams show a magnetised steel rod inside a solenoid connected to a potentiometer.
In diagram 1, the potentiometer is connected to a d.c. power supply.
In diagram 2, the potentiometer is connected to an a.c. power supply.
diagram 1
diagram 2
Which action would demagnetise the piece of steel?
In diagram 1, move the potentiometer slide from P to Q.
In diagram 1, move the potentiometer slide from Q to P.
In diagram 2, move the potentiometer slide from R to S .
In diagram 2, move the potentiometer slide from S to R.
The diagram shows the magnetic field around a solenoid carrying an electric current.
What happens to the strength of the magnetic field and the distance between the field lines when the current is increased?
strength of
magnetic field
distance between
field lines
decreases
decreases
decreases
increases
increases
decreases
increases
increases
The diagram shows a solenoid carrying an electric current.
Which row compares the strength of the magnetic field due to the solenoid at points Y and Z with the strength of the magnetic field at point X ?
magnetic field
strength at Y
magnetic field
strength at Z
equal to X
less than X
equal to X
greater than X
greater than X
less than X
greater than X
greater than X
Which diagram represents the strength and direction of the magnetic field around a current-carrying conductor? (The direction of the current is into the page.)
A current in a solenoid produces a uniform magnetic field inside the solenoid. The magnetic field direction is due east.
Which changes will produce a stronger magnetic field with a direction due west?
Use a smaller current and turn the solenoid through .
Use a smaller current and reverse the current.
Use a larger current and turn the solenoid through .
Use a larger current and reverse the current.
The diagram shows the pattern of the magnetic field due to the current I in a straight wire.
Which row is correct?
direction of field
relative
strength of field
X
greater at P than Q
Y
greater at P than Q
X
greater at Q than P
Y
greater at Q than P
Three statements about a relay are given.
1 A relay has a coil that becomes a temporary magnet when in operation.
2 A large current in a relay coil is used to switch off a smaller current.
3 A small current in a relay coil is used to switch on a larger current.
Which statements are correct?
1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3